--- /dev/null
+%% Copyright (c) 2011, INRA
+%% 2007-2011, David Legland <david.legland@grignon.inra.fr>
+%% 2011 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
+%%
+%% All rights reserved.
+%% (simplified BSD License)
+%%
+%% Redistribution and use in source and binary forms, with or without
+%% modification, are permitted provided that the following conditions are met:
+%%
+%% 1. Redistributions of source code must retain the above copyright notice, this
+%% list of conditions and the following disclaimer.
+%%
+%% 2. Redistributions in binary form must reproduce the above copyright notice,
+%% this list of conditions and the following disclaimer in the documentation
+%% and/or other materials provided with the distribution.
+%%
+%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+%% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+%% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+%% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+%% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+%% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+%% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+%% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+%% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+%% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+%% POSSIBILITY OF SUCH DAMAGE.
+%%
+%% The views and conclusions contained in the software and documentation are
+%% those of the authors and should not be interpreted as representing official
+%% policies, either expressed or implied, of copyright holder.
+
+%% -*- texinfo -*-
+%% @deftypefn {Function File} {@var{b} = } isPointOnRay (@var{point}, @var{ray})
+%% @deftypefnx {Function File} {@var{b} = } isPointOnRay (@var{point}, @var{ray}, @var{tol})
+%% Test if a point belongs to a ray
+%%
+%% @var{b} = isPointOnRay(@var{point}, @var{ray});
+%% Returns @code{true} if point @var{point} belongs to the ray @var{ray}.
+%% @var{point} is given by [x y] and RAY by [x0 y0 dx dy]. @var{tol} gives the
+%% tolerance for the calculations.
+%%
+%% @seealso{rays2d, points2d, isPointOnLine}
+%% @end deftypefn
+
+function b = isPointOnRay(point, ray, varargin)
+
+ % extract computation tolerance
+ tol = 1e-14;
+ if ~isempty(varargin)
+ tol = varargin{1};
+ end
+
+ % number of rays and points
+ Nr = size(ray, 1);
+ Np = size(point, 1);
+
+ % if several rays or several points, adapt sizes of arrays
+ x0 = repmat(ray(:,1)', Np, 1);
+ y0 = repmat(ray(:,2)', Np, 1);
+ dx = repmat(ray(:,3)', Np, 1);
+ dy = repmat(ray(:,4)', Np, 1);
+ xp = repmat(point(:,1), 1, Nr);
+ yp = repmat(point(:,2), 1, Nr);
+
+ % test if points belongs to the supporting line
+ b1 = abs ( (xp-x0).*dy - (yp-y0).*dx ) ./ hypot(dx, dy) < tol;
+
+ % check if points lie the good direction on the rays
+ ind = abs (dx) > abs (dy);
+ t = zeros (size (b1));
+ t(ind) = (xp(ind)-x0(ind))./dx(ind);
+ t(~ind) = (yp(~ind)-y0(~ind))./dy(~ind);
+
+ % combine the two tests
+ b = b1 & (t >= 0);
+
+endfunction
+
+%!shared ray
+%! p1 = [10 20];
+%! p2 = [80 20];
+%! ray = createRay (p1, p2);
+
+%!assert (isPointOnRay([10 20], ray));
+%!assert (isPointOnRay([80 20], ray));
+%!assert (isPointOnRay([50 20], ray));
+%!assert (isPointOnRay([50 20+1e-3], ray,1e-2));
+%!assert ( !isPointOnRay([50 20+1e-3], ray,1e-4));
+%!assert ( !isPointOnRay([9.99 20], ray));
+%!assert ( !isPointOnRay([80 20.01], ray));
+%!assert ( !isPointOnRay([50 21], ray));
+%!assert ( !isPointOnRay([79 19], ray));